2-Octenal (CAS 2363-89-5) — Green Top to middle Note Fragrance Ingredient

ByThe Good Scents
Green · Floral

2-Octenal

CAS 2363-89-5

Origin
synthetic
Note
Top to middle
IFRA
Use with awareness
Data as of: Apr 2026

What Is 2-Octenal?

2-Octenal is a synthetic fragrance ingredient with a strong, green, fatty odor reminiscent of cucumber peels and freshly cut grass. It’s used in perfumery to add crisp vegetal notes. This aldehyde contributes to modern green fragrances, often paired with citrus or aquatic accords for freshness.

Safety Profile

USE WITH AWARENESS
Generally safeUse with awarenessProfessional use
✓ IFRA approved within limits
⚠ Moderate skin sensitization potential
CAS
2363-89-5
Formula
Mixture
MW
Variable
Odor Family
Green · Floral
Layer 1 · Enthusiast

What Does 2-Octenal Smell Like?

2-Octenal bursts with an intense green character – imagine crushing cucumber stems between your fingers with an underlying fatty, waxy quality like the white inner rind of melons. The top note has almost metallic sharpness that evolves into softer leafy tones. In drydown, it leaves a trace of raw potato skin and wet vegetation, making it ideal for creating ‘stemone’ effects in floral compositions or adding dimension to marine accords.

Scent Profile
Layer 2

2D Molecular Structure

2-Octenal

SMILES: CCCCCC=CC=O

Chemistry, Properties & Perfumer Guide

The Chemistry

2-Octenal is an α,β-unsaturated aldehyde belonging to the octenal family. As a C8 aldehyde, it’s synthesized via oxidation of corresponding alcohols or through aldol condensation reactions. The trans-isomer predominates in fragrance applications due to its more pronounced odor characteristics. Its electrophilic nature makes it reactive with nucleophiles, requiring stabilization in formulations.

Physical & Chemical Properties

Boiling Point~170-175 °C (estimated)
Vapor PressureModerate (estimated)

Perfumer Guide

Note Position
Top to middle
Volatility
Medium (1-3 hours)
Blending
Good with citrus and woody notes
ApplicationTypical %RangeNotes
Fine Fragrance0.1-0.5%Up to 1%Green modifier
Functional Fragrance0.01-0.1%Up to 0.3%Freshness booster

Classic Accords

Tip: Stabilize in ethanol-heavy bases to prevent polymerization.

Alternatives & Comparisons

1
Hexenal CAS 6789-80-6

Shorter chain version with more intense green character but less fatty depth.

2
Nonadienal CAS 557-48-2

For more pronounced cucumber-melon effects with better stability.

Layer 3

Safety, Regulatory & Sustainability

⚠ Regulatory Disclaimer

General reference only. Consult current IFRA Standards Library before formulating.

IFRA Status

No specific restrictions under IFRA 49th Amendment.

GHS Classification

H315 Skin irritation H319 Eye irritation

RIFM Assessment

RIFM evaluation ongoing – preliminary data suggests moderate sensitization potential at current use levels.

Sustainability

Synthesized from petrochemical feedstocks via efficient catalytic processes. No known ecological toxicity concerns at production scale. Not biodegradable but used at trace levels unlikely to accumulate in environment.

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References

    Data: PubChem (NIH), PubMed, RIFM, IFRA. Last reviewed: Apr 2026.

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    Ingredient Data Sheet

    CAS 2363-89-5

    Physical Properties

    Molecular Weight126.2 g/mol🔬 PubChem
    LogP (Octanol-Water)2.6🔬 PubChem
    Boiling Point174 °C🔬 EPA CompTox
    Vapor Pressure0.59 mmHg @ 25°C📊 OPERA
    Flash Point65.6 °C🔬 EPA CompTox
    Involatility Index0.0566💻 Calculated
    log Kp (skin permeability)-1.624💻 Calculated

    Volatility & Performance

    Fragrance NoteTop💻 Calculated
    Volatility ClassSlow💻 Calculated
    Persistence Score0.5 / 5💻 Calculated

    Odor & Flavor

    2-Octenal has a peculiar green-leafy odor, less fatty than octanal. This compound is also reported as having orange, honey-like, cognac-like aroma.📖 Fenaroli

    Sensory Thresholds

    Odor Detection Threshold8.1599 ppm (n=8)📖 van Gemert

    Regulatory Status

    IOFI ClassificationNature Identical📖 Fenaroli
    Data Sources & Attribution
    Physical data: PubChem (NIH/NLM), U.S. EPA CompTox Dashboard, EPA OPERA models, RDKit. Odor & flavor: Arctander (Perfume & Flavor Chemicals), Fenaroli's Handbook of Flavor Ingredients, Leffingwell. Thresholds: van Gemert (Compilations of Odour Threshold Values). Regulatory: IFRA Standards 51st, FEMA GRAS. Trade names: Surburg (Common Fragrance & Flavor Materials). All data compiled and cross-referenced for perfumertools.com.

    Physicochemical Properties

    DTXSID: DTXSID0062349

    Physical Properties

    Molecular Weight 126.199 g/mol🔬 EPA CompTox
    Density 0.84 g/cm^3🔬 EPA CTX
    Boiling Point 184.273 °C📊 OPERA
    Melting Point -8.935 °C📊 OPERA
    Flash Point 64.319 °C📊 OPERA
    Refractive Index 1.433 Dimensionless📊 OPERA
    Molar Volume 151.523 cm^3/mol📊 OPERA

    Partition & Solubility

    LogP (Octanol-Water) 2.715 Log10 unitless📊 OPERA
    LogD (pH 5.5) 2.715 Log10 unitless📊 OPERA
    LogD (pH 7.4) 2.715 Log10 unitless📊 OPERA
    LogKoa (Octanol-Air) 4.52 Log10 unitless📊 OPERA
    Water Solubility 0.009 mol/L📊 OPERA
    Henry's Law Constant 0 atm-m3/mole🔬 EPA CTX

    Transport Properties

    Vapor Pressure 0.605 mmHg📊 OPERA
    Viscosity 1.035 cP📊 OPERA
    Surface Tension 25.458 dyn/cm📊 OPERA
    Thermal Conductivity 145.757 mW/(m*K)📊 OPERA

    Molecular Descriptors

    Topological Polar Surface Area 17.07 Ų💻 Computed
    H-Bond Donors 0 count💻 Computed
    H-Bond Acceptors 1 count💻 Computed
    Rotatable Bonds 5 count💻 Computed
    Aromatic Rings 0 count💻 Computed
    Molar Refractivity 39.356 cm^3/mol📊 OPERA
    Polarizability 15.602 Å^3📊 OPERA

    Data Sources:

    🔬 EPA Experimental data from U.S. EPA CompTox Chemicals Dashboard & CTX APIs. 📊 OPERA Predicted using EPA's OPERA QSAR models. 💻 Computed Calculated from SMILES using RDKit.

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